1. Field of the Invention
The present invention generally relates to an image display apparatus with a relatively large screen for use in a liquid crystal projector, a liquid crystal television, etc. More particularly, the present invention pertains to an image display apparatus using simple matrix liquid crystal display apparatus, such as an STN liquid crystal display apparatus.
2. Description of the Related Art
It is required that a liquid crystal display (LCD) apparatus for a television set should have high performance and good quality, such as high resolution, fine gray scales, quick response and high contrast.
There are two type LCD display apparatus: a simple matrix LCD apparatus and a TFT LCD apparatus. The TFT LCD apparatus is considered to be more excellent in the quality of an image and a response speed. The simple matrix type LCD apparatus has the following two shortcomings:
i) A response speed is low.
ii) Because of high duty, the margin is small and contrast is low.
Particularly, the response speed of the simple matrix LCD apparatus is low. If STN liquid crystal is used, the response speed will be lower even though the contrast is improved.
In a conventional LCD apparatus, since the quality of an image is determined by the number of bits constituting a control signal which defines an image, the circuit scale and the number of wirings have to be increased to acquire a high-quality display. In a liquid crystal driving circuit which displays an image on an LCD with gray scales by means of pulse width modulation, for example, if the number of bits of the control signal can be decreased, the number of wirings and the circuit scale will also be reduced, ensuring a lower cost for the apparatus accordingly. It is however, difficult to improve the quality of an image without reducing the number of bits.